At present, human-machine interface technologies are developing rapidly, among which OLED display, as a new type of display, is favored by many people due to its advantages of self-luminous panel, high brightness, high reaction speed, and low power consumption, and is widely used with good prospect at present.
Besides, as a new type of input device, touch screen is replacing keyboard, mouse and other traditional input devices gradually due to the advantages that it is lighter, thinner and more humanised. Touch screen users can conduct input operation while browsing contents displayed on the screen, which makes human-machine communication very convenient and accurate. Therefore, touch screens are widely used in PDAs, mobile phones, GPS and other portable electronic products.
In view of many advantages of OLED and touch device, more and more attention is paid to the development of OLED display with an integrated touch function. FIG. 1 shows a conventional OLED touch display 1. The touch display 1 comprises an upper substrate 11, a lower substrate 12, a capacitive touch module 13 between them, an OLED display module 14, and a sealing glue layer 15. The upper substrate 11 comprises an upper surface 111 used for touch and a lower surface 112 encapsulated inside the display. The capacitive touch module 13 is configured on the lower surface 112 of the upper substrate 11 and comprises a first conducting layer 131, a second conducting layer 133, and an insulating layer 132 between the two. The OLED display module 14 is disposed on the inner surface 121 of the lower substrate 12, while the external surface 122 is exposed outside the display. The OLED display structure 14 comprises a hole injection layer 141, an organic emitting layer 142, and an electron injection layer 143. Integrating the touch module 13 into the OLED display 14 can effectively reduce thickness of the display 1.
However, there is only one insulating layer 132 between the first conducting layer 131 and the second conducting layer 133 of the touch module 13, thickness of which is less than 2 μm in general and therefore, comparatively, large coupling capacitance will be generated between the first conducting layer 131, and the second conducting layer 133 due to close distance. In practical detection, besides finger touch, capacitance exists between a finger and a panel. Other background capacitances take place between two electrode layers or between electrodes and surrounding environment. Larger the background capacitance is, larger the interference in signal detection will be. Large coupling capacitance generated between the first conducting layer 131 and the second conducting layer 133 constitutes the component of the background capacitance and therefore, the coupling capacitance will affect the accuracy for detection of capacitance touch location.